Roadway construction and method therefor

ABSTRACT

A roadway has a containerized roadbed of a width sufficient to support a road surface and a depth sufficient to extend below the frost line of the earth in the area; the containerized roadbed has an outer enveloping wall of suitable elastomeric material which contains therein suitable filler material such as, for example, dirt, sand and rock; the containerized roadbed is evacuated to remove moisture from the filler material and hermetically sealed; a suitable road surface, as for example a layer of concrete, is formed atop the containerized roadbed.

United States Patent Cushman 1 51 Sept. 30, 1975 [54l ROADWAYCONSTRUCTION AND 3.279.334 l0/l966 Quartararo 404/31 3,424.647 l/l969Callahan 52/l69 X 3,474.625 10/1969 Draper 52/515 X [75] Inventor:Walton W. Cushman, Fraser. MlCl'l 35773 3 5 197 r", 404 31 3,646.72l3/1972 Becker 5Z/6l8 [73] Assgnw Stcrlmg 3.659.812 5/1972 Carlsson404/19 x M1ch.

[ Filed? July 1973 Fri/mu E.\amine1'Nile C. Byers, Jr. [2]] Appl No;376,396 Attorney. Agent, 01' Firm-Lon H. Romzlnski Related U.S.Application Data 5 [63] Continuation of Scr. No. 144.447. May 18. 1971.ABSTRACT abandoned. A roadway has a containcrized roadbed of a widthsufficicnt to support a road surface and a depth sufficient [52 U.S. Cl.404/27 to extend below the frogt line of the earth in the area; [51]int. Cl. EOIC 3/00 the com-ainerized roadbcd has an outer enveloping[58] Field Of earch 0 wall of suitable elastomeric material whichcontains 40 /1 306/4533 therein suitable filler material such as, forexample.

dirt, sand and rock; the containerizcd roadbed is evac- [56] ReferencesCited uatcd to remove moisture from the filler material and UNITEDSTATES PATENTS hermetically sealed; a suitable road surface. as for ex-1 565 682 12/1925 Struhzm 404/18 mplc concmtcis formed atop the Comm2.044498 6/1936 Pearce 404 28 crizcd rofldbcd- 2.211.649 8/1940 Drurv404/28 2.649.101 8/1953 Suits 52/2 2 6 Drawmg Flgures US. Patent Sept.30,1975

I N VEN TOR. %Zf0z2 W Qzszzzcm ATTO RNEYS ROADWAY CONSTRUCTION ANDMETHOD THEREFOR RELATED APPLICATION This application is a continuationof my copending application Ser. No. 144,447 filed May 18, I971 nowabandoned, for Roadway Construction and Method Therefor.

According to the disclosure :1 method of constructing a roadway includesexcavating a ditch of the required width and depth with the depth beingofa dimension to sufficiently extend below the natural frost line,placing a suitable liner of elastomeric material in the trench or ditch,filling the liner with material removed in the process of forming theditch or trench, hermetically sealing the liner as to contain the fillermaterial within the liner, evacuating the interior of the liner as tothereby remove any moisture from within the liner and to atmosphericallycompact the material within the liner, and then placing a layer ofmaterial atop the liner to form a road surface.

BACKGROUND OF THE INVENTION Heretofore, various methods have beenproposed and employed in the construction of roadways. However, suchroadways, especially in areas where the earth is subjected alternatelyto freezing and thawing, undergo progressively increasing deteriorationand breakage. Such deterioration is principally caused by the moisturecontained in the roadbed. That is, because of rain and sub-surfaceseepage the material forming the roadbed usually contains a degree ofwater which, when freezing conditions occur, freezes and expands. Suchexpansion results in the uneven applicationof upward forces against thematerial forming the road surface causing cracks and other failurestherein. The same results are obtained, for example, during seasonalchanges where snow may be deposited on and about the roadway one daythen melt and after melting again freeze because of atmospheric changes.

Those skilled in the art have been aware of the damage caused by thefreezing of water because of the elaborate steps taken to try to providematerial for the roadbed which would enhance drainage. However, as isevident from the damaged state of roadways which are more than a yearold indicates that the prior art roadbeds still contain a high degree ofwater and the roadways are still just as susceptible to damage fromcyclic freezing and thawing of such water.

Accordingly, the invention as herein disclosed and described isprimarily directed to the solution of the above as well as other relatedproblems.

SUMMARY OF THE INVENTION According to the invention, a roadway comprisesa roadbed, and a road surface carried atop said roadbed, said roadbedcomprising a relatively flexible and moisture inpervious outer containerhaving an upper wall surface a lower wall surface side wall portions andend wall portions, and filler material fillingthe interiorof said outercontainer, said outer container being hermetically sealed with saidinterior and said filler material contained therein being evacuated to agas pressure of a magnitude substantially less than the magnitude of thesurrounding ambient atmospheric pressure.

DESCRIPTION OF THE DRAWINGS In the drawings, wherein for purposes ofclarity certain details and/or elements may be omitted from one or moreviews:

FIG. 1 is a perspective view ofa roadway, embodying the teachings of theinvention, shown in cross-section at one end thereof and with some ofthe surrounding earth removed for purposes of clarity; and

FIGS. 2, 3, 4, 5 and 6 pictorially illustrate the various steps employedin constructing the roadway of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in greater detailto the drawings, FIG. 1 illustrates a roadway 10 comprised of acontainerized roadbed 12 situated generally within a ditch or trench 14and a road surface 16 formed thereatop as by a concrete slab 18.

In the embodiment shown, the trench 14 would be formed as to have thelower surface 20 thereof below the level of the natural frost line asdepicted generally at 22. The frost line is, of course, the depth of theterrain to which freezing temperatures above the surface of the terrainwill be effective in freezing that terrain as well as any moisturecontained therein. Therefore, a frost line of, for example, three feetwould mean that any material or moisture at such a depth greater thanthree feet from the surface would not become frozen due to prolongedfreezing temperatures above the surface.

The roadbed 12, as generally shown in both FIGS. I and 4, is comprisedof an outer container 24 which has upper and lower walls 26, 28, opposedside walls 30, 32 and opposed end walls 34, 36. The container 24 may beformed of, for example and not by way of limitation a suitableelastomeric material such as polyethylene or polypropylene. Suchmaterial would be impervious to water vapor at pressures at least equalto and at least somewhat greater than atmospheric pressure.

The interior of the container 24 would be filled with material as, forexample, was excavated during the formation' of the trench l4 and theside walls 30, 32, end walls 34, 36 and top wall 26 would be formed asby wrapping the material (which may originally be in sheet form) formingthe container 24 about such filler material and hermetically sealing theedges of such material. Once the roadbed is thereby formed, the roadsurface can be layed atop thereof in any conventional manner as by thepouring of a concrete slab 18.

One method particularly suitable for the construction of such a roadway10 is illustrated by FIG. 2, 3, 4, 5 and 6 to which specific referencewill now be made.

The first step of the disclosed method would be the formation of asuitable trench 14 in the earth 38 as fragmentarily illustrated inperspective .and crosshatched as in FIG, 2. The tre'nch would beelongated having a lower surface 20, below the natural frost line 22,and opposed side walls 40 and 42 (which need not be substantiallyperpendicular to the lower surface 20 as shown). By way of example, theditch or trench 14 may, arbitrarily be 20.0 feet wide by 4 feet 8 inchesdeep onthe assumption that the road surface slab 18 will be 8.0 inchesthick. The dirt, sand, rock or other material removed during theexcavation of the trench 14 may be deposited in close proximity to thetrench 14 for purposes to be described.

After the trench 14 is properly formed, a liner or sheet 44 ofelastomeric material is laid within the trench 14 as to have a bottomportion thereof 28 lying against and supported by the lower surface oftrench 14 and upwardly directed portions 30 and 32 of the sheet 44juxtaposed to side walls 40 and 42 of the trench 14. The sheet 44 wouldcontinue having portions 26a and 26b overlying the surrounding surfaceof the ground 38 as generally shown in FIG. 3.

After the liner 44 is placed within the trench 14, it may be filled withthe material excavated during the formation of the trench 14. The liner44 is then folded, much in the manner as in wrapping a package, therebyforming end walls 34 and 36 as well as employing portions 26a and 26b toform the upper wall 26. When the sheet 44 is thereby folded it assumes aconfiguration somewhat as depicted in FIG. 4 wherein an outer container46, which may have seams 48, 50, S2, 54, 56, 58 and 60 relativelytightly contains the filler material 62 (in this case, the earthexcavated during formation of the trench 14). The seams 4860 are thenhermetically sealed by any suitable means such as, for example, throughthe application of a suitable impervious cement, adhesive or tape, or,by means of the application of heat thereto as to cause a heat weld ofthe seams.

Next, as generally depicted in FIG. 5, suitable aperture means 62 isformed through, for example, the upper wall 26 of the container 46 and asuitable conduit-like adapter 64 is inserted therein and operativelyconnected to a vacuum pump 66. The adapter 64 may, as shown, include arather large annular flange portion (which may be flexible) so as to inand of itself act as a seal during the time that the vacuum pump 66 isenergized.

Vacuum, created by the pump 66, is thereby applied to the interior ofcasing 46 and may be in the order approaching l4.7 pounds per squareinch. Generally, the higher the value of the vacuum, the better theresults will be.

Because of the application of such vacuum at least two beneficialresults are obtained. First, whatever moisture was contained within thecasing 46 or the filler material therein is removed by the lowering ofthe pressure within casing 46. That is, once the pressure within casing46 is reduced, the vapor pressure of the moisture causes the interior ofthe casing to be filled with water vapor which, in turn, isprogressively and continually removed by the action of the vacuum pump66. The vacuum thereby produced is applied to the interior of the casing46 for a time sufficient to assure the removal of substantially all ofthe water vapor contained therein.

As somewhat pictorally represented in FIG. 5, the adapter 64 may includea valve member 68 which can be actuated to a closed position after theinterior of the casing 46 has been sufficiently evacuated therebysealing the interior of casing 46 from the ambient atmosphere. It shouldbe apparent that the relative sizes of the adapter 64 and casing 46 areshown out of proportion merely for purposes of illustration anddisclosure. In reality any suitable connection could be made as betweenthe interior of casing 46 and pump 66 including tubing means which couldbe collapsed upon a force greater than 14.7 pounds per square inch inorder to close-off the interior of the casing 46 with respect to theambient atmosphere. Such suitable adapter means as 64 could then befurther sealed with cement, adhesive or heat in order to assure thehermetic sealing the casing 46.

The second major benefit of such evacuation of the casing 46 is theresulting strength and rigidity of the roadbed 12. That is, because ofthe flexibility of the liner of casing 46, when the interior thereof isevacuated the resulting pressure differential between the interior andthe atmospheric pressure externally thereof causes the filler materialwithin the casing 46 to become compacted and extremely rigid. Therigidity of the roadbed 12 becomes much greater than what can beachieved with the use of crushed stone as is employed by the prior art.The net result is that a beam effect is obtained with the materialscontained within the casing reacting against atmospheric pressure.

After the roadbed 12 has been formed, evacuated and hermetically sealedas set forth above, a suitable road surface is formed atop the roadbedas by, for example, pouring a layer of concrete to form a slab 18 asgenerally depicted in FIGS. 1 and 6.

Depending upon the constituency of the earth where I such a roadway isbeing constructed, there may be instances where considerable care wouldhave to be exercised when replacing the excavated earth to avoidpuncturing the elastomeric sheet or liner 44. Accordingly, to assist inavoidance of such punctures, the elastomeric sheet may be first linedwith such materials as, for example, sand, sawdust, building paper, oldnewsprint or straw (as generally depicted by the layer 70 in FIG. 6)since none of these materials will decompose after evacuation and eachwill compress sufficiently to offer adequate strength.

In view of the above, it can be seen that the invention provides aroadway having an extremely rigid roadbed which is substantially freefrom water vapor thereby not being susceptible to upheavals due to thefreezing and expansion of moisture as in the prior art.

In practicing the method herein disclosed, it should be apparent that itis not absolutely necessary to first form a trench or ditch 14. That is,the roadbed 12 may be formed, as generally described above, and placedatop the surface of the earth after which, as by backfilling or gradingoperations the dirt or earth can be brought up against the sides of theroadbed 12 'and graded to a height sufficient to, in effect, place thelower wall 28 of the casing 46 below the resulting frost line. This, ofcourse, becomes of major benefit where a roadway is being constructedthrough hilly terrain and it is desired to reduce the relative heightsof the peaks and valleys of the general path of the roadway.

This is, some of the dirt removed in cutting away a part i of a hill canbe graded downwardly and about a roadbed 12 formed atop the surfacewithin the adjoining valley.

Even though it is believed apparent, it should nevertheless be madeclear that the invention is not limited to the use of sheet-likeelastomeric material as at 44. On the contrary, it is also contemplatedthat such material could be preformed so as to generally define aflexible or collapsible countainer having already formed end walls, sidewalls and bottom wall thereby reducing the number of seams to behermetically sealed. Such could be made in modular lengths if desired.

Further, although the invention has been presented as solving a longstanding problem, namely, the damage done to prior art roadways due toroadbed upheaval arising out of the freezing and thawing of moisturewithin the roadbed, the invention can. nevertheless, be practical ingeographical areas which are not subjected to freezing conditions. .Insuch situations it would not be necessary, for purposes of avoidingsurface upheavals due'to frost, to dig or otherwise provide a ditch ortrench for the reception therein of the roadbed 12. In such situationsthe roadbed 12 could be formed as previously described and placed atopthe surface of the terrain. The benefit derived would be the rigidity ofthe evacuated roadbed 12. That is, it would continue to act as a rigidbeam because of the atmospheric pressure continually holding all of theparticles forming the filler of the roadbed, in a compacted condition.

Although only one preferred embodiment and se-.

lected modifications of the invention have been disclosed and described,it is apparent that other embodiments and modifications of the inventionare possible within the scope of the appended claims.

I claim:

1. A roadway, comprising a roadbed, and a road surface carried atop saidroadbed, saidroadbed comprising a relatively flexible and moistureimpervious outer container of exclusively plastic material having anupper wall surface a lower wall surface side wall portions and end wallportions, filler material filling the interior of said outer container,said outer container being hermetically sealed with said interior andsaid filler material contained therein being evacuated to a gas pressureof a magnitude substantially less than the magnitude of the surroundingambient atmospheric pressure, said plastic material being elastomeric,said lower wall surface of said outer container being situated at alevel below the frost line of the surrounding earth, a trench excavatedin the earth, said trench having a lower surface below the frost line ofthe surrounding earth, and wherein said lower wall surface of said outercontainer is supported by said lower surface of said trench, and whereinsaid filler material comprises such earth as was obtained in theexcavation of said trench.

2. A method of constructing a roadway, comprising the steps of formingan outer casing from a relatively flexible and moisture imperviousexclusively plastic material, filling said casing with a suitable fillermaterial, hermetically sealing said outer casing, subjecting theinterior of said outer casing and said filler material contained thereinto a process of evacuation so as to produce within said outer casing agas pressure of a magnitude substantially less than the magnitude of thesurrounding ambient atmosphere pressure, laying a layer of material atopsaid outer casing for forming a road surface, digging a trench withinthe earth so as to have a lower surface of said trench at a level belowthe natural frost line of the surrounding earth, forming said outercasing as to have an upper wall surface a lower wall surface opposed endwall portions and opposed side wall portions, placing said casing withinsaid trench as to have said lower wall surface supported by said lowersurface of said trench, returning the earth excavated during digging ofsaid trench to the interior of said outer casing so as to thereby format least a portion of said filler material, and wherein the step ofevacuation includes the removal of at least a substantial amount of anywater vapor contained within said outer casing.

1. A roadway, comprising a roadbed, and a road surface carried atop saidroadbed, said roadbed comprising a relatively flexible and moistureimpervious outer container of exclusively plastic material having anupper wall surface a lower wall surface side wall portions and end wallportions, filler material filling the interior of said outer container,said outer container being herMetically sealed with said interior andsaid filler material contained therein being evacuated to a gas pressureof a magnitude substantially less than the magnitude of the surroundingambient atmospheric pressure, said plastic material being elastomeric,said lower wall surface of said outer container being situated at alevel below the frost line of the surrounding earth, a trench excavatedin the earth, said trench having a lower surface below the frost line ofthe surrounding earth, and wherein said lower wall surface of said outercontainer is supported by said lower surface of said trench, and whereinsaid filler material comprises such earth as was obtained in theexcavation of said trench.
 2. A method of constructing a roadway,comprising the steps of forming an outer casing from a relativelyflexible and moisture impervious exclusively plastic material, fillingsaid casing with a suitable filler material, hermetically sealing saidouter casing, subjecting the interior of said outer casing and saidfiller material contained therein to a process of evacuation so as toproduce within said outer casing a gas pressure of a magnitudesubstantially less than the magnitude of the surrounding ambientatmosphere pressure, laying a layer of material atop said outer casingfor forming a road surface, digging a trench within the earth so as tohave a lower surface of said trench at a level below the natural frostline of the surrounding earth, forming said outer casing as to have anupper wall surface a lower wall surface opposed end wall portions andopposed side wall portions, placing said casing within said trench as tohave said lower wall surface supported by said lower surface of saidtrench, returning the earth excavated during digging of said trench tothe interior of said outer casing so as to thereby form at least aportion of said filler material, and wherein the step of evacuationincludes the removal of at least a substantial amount of any water vaporcontained within said outer casing.